That behaviour is pretty random, but getting more likely the more data i copy (like: 100MB = mostly works, 1GB: almost never works).

When using the orginal firmware, no errors occur, so i exclude hardware defects.

This task depends upon

Closed by MichaelGiacomelli (saratoga)
Saturday, 28 April 2012, 00:04 GMT Reason for closing: DuplicateAdditional comments about closing: This is so similar to FS#12184 I think it would
be better to have it handled in there.

Its a Fuze V1.
Yes, FS#12184 sounds pretty much like my problem. Windows does not recognize the lost connection for long time. sometimes applications interacting with the device (Mediamonkey, VLC) giving error messages or just crash.